Cap 5.0-10.0 mm long by 5.0-7.0 mm wide, pendulous cupulate, then pleurotoid to broadly fan-shaped; margin incurved, decurved in age, sometimes wavy; surface whitish, sparsely pubescent near the base, elsewhere glabrous or matted-fibrillose when dry; context very thin, less than 1 mm, watery-white; odor and taste mild.
Hymenium nearly smooth at first, soon developing gill-like folds radiating from a basal attachment point, subdistant, eventually wavy to contorted and intervenose; whitish at all stages.
Stipe absent to greatly reduced, fruiting body eccentric or lateral in attachment.
Spores 5.0-6.5 x 4.5-6.0 µm, hyaline in water, inamyloid, subglobose to broadly tear-shaped, smooth, thin-walled, hilar appendage conspicuous, up to 2.0 microns long, contents granular; spore print not seen.
Scattered to gregarious on moss-covered banks; fruiting from mid to late winter.
Unknown, totally insignificant.
As indicated by the species name, Rimbachia bryophila is closely associated with mosses. Some authors suggest that the relationship may be parasitic which could explain why patches of dead moss are frequently found close to fruitings. Fieldmarks include a small, laterally attached, thin white cap, lack of stipe, and gills reduced to intervenose folds. The latter feature helps distinguish this fungus from diminutive species of Crepdiotus, Pleurotus and Hohenbuehelia.